Investors in Boeing, which calls its newest plane a Dreamliner, had feared that yesterday's blaze meant that the battery problem that had grounded the whole fleet of such planes in January had not been fixed.
News of the fire sent Boeing shares down 4.7 per cent yesterday.
Britain's Air Accidents Investigation Branch said today there was "no evidence of a direct causal relationship" between the Dreamliner's batteries and the fire.
"There has been extensive heat damage in the upper portion of the rear fuselage, a complex part of the aircraft ... it is clear that this heat damage is remote from the area in which the aircraft main and APU (Auxiliary Power Unit) batteries are located," it said in a statement.
Ethiopian Airlines said it is continuing to operate its fleet of 787s despite the investigation, which will take at least several more days to be completed.
The airline's chief executive, Tewolde Gebremariam, told The Associated Press today that there is "no flight safety issue" with the 787s and that Ethiopian Airlines, like other operators, hasn't made changes regarding the planes.
Yesterday's incident drew renewed attention to the future of Boeing's most technologically-advanced airliner and forced runways at Heathrow, one of the world's busiest airports, to shut down for nearly an hour.
In January, the Dreamliner was grounded for months following two incidents relating to overheating lithium-ion batteries on separate planes.